With rapid developments of terminal technology, intelligent terminals are more and more popular, and have become important devices in lives of people. People learn and are entertained by the intelligent terminals.
Determination of a proximate state or distant state between the intelligent terminals and an external object, for controlling on and off states of display screens of the intelligent terminals, is a necessary function of the intelligent terminals. The intelligent terminals detect the proximate state and distant state between the intelligent terminals using an infrared emitter and an infrared receiver. The infrared emitter emits infrared light, and an object reflects the infrared light to form reflected light. After the infrared receiver receives the reflected light, the proximate state and distant state of the intelligent terminals are determined, based on intensity of the reflected light.
However, in actual use of the intelligent terminals, long distance between the infrared emitter and the infrared receiver causes reception failure of the reflected light to the infrared receiver, when the external object approaches the intelligent terminals. When the infrared emitter and the infrared receiver are too close each other, and the intelligent terminals are far away from the external object, part of the infrared light emitted by the infrared emitter can directly enter the infrared receiver due to diffraction of the infrared light inside the intelligent terminals, so that the infrared receiver has a large basic value regarding the detection. Since the external object is away from the infrared receiver, small intensity changes of the reflected light can be detected by the infrared receiver after the reflected light enters the infrared receiver. Therefore, sensitivity of the infrared receiver is very low, which will cause errors or detection omissions, thereby causing inaccurate control of on and off states of the display screens of the intelligent terminals.